I used outlook 2000, with which i could send & recieve my emails (via our company exchange server)
I upgraded to outlook 2003 (in fact the whole office...), and I fail to SEND emails. I still receive them, but when I send my emails they stay in the Outbox folder.
Just for fun, I go to another computer, open outlook 2000, open outbox, open the email, click SEND -> the email is sent!!!